Recent studies in this laboratory have suggested that patients with Hodgkin's disease may have significant abnormalities of immune function unassociated with the presence of active disease. Assays of non-specific immunity are abnormal in patients with Hodgkin's disease cured by MOPP chemotherapy. These abnormalities cannot be attributed to the chemotherapy since they are not present in patients with diffuse histiocytic lymphoma cured by similar chemotherapy regimens. T lymphocytes in both untreated and cured patients with Hodgkin's disease have increased sensitivity to suppression by normal immune regulatory cells. This has been shown for both a macrophage suppressor cell and a T cell suppressor induced by concanavalin A. Both suppressor systems operate independently of prostaglandin E. A new serologic specificity closely linked to the HLA-Dr locus has been observed in cured Hodgkin's patients. Studies are in progress to define the genetics of these immune abnormalities by studying families of affected patients.